1. Field of the Invention
It is frequently necessary to send mechanical devices through the interior of a pipeline. One reason for using a device that is transmitted through a pipeline, usually referred to as a "pig", is for cleaning the interior surface of the pipeline. Another use for a pipeline pig is for separating one fluid medium from another. Sometimes pipeline pigs are used for pushing out entrapped liquids in a gas transmitting pipeline. Another and very important reason for sending pigs through a pipeline is for gaining information as to the condition of the pipeline. Such pigs are frequently referred to as "instrumentation pigs" and these type of devices can be used to provide information as to the ovality of the pipeline, the interior diameter of various sections of the pipeline, the occurrence of dents, buckles or bulges in the pipeline wall, the detections of bends or changes in direction of the pipeline and the occurrence of corrosion in the pipeline interior or exterior walls.
Pipeline pigs, particularly of the instrumentation type, normally employ cups formed of resilient material, such as urethane. The cups serve two basic functions, that is, (1) they support the body of the pig within the interior of the pipeline and (2) at least one cup for each pig provides a piston-like action so that the flow of the fluid medium, whether liquid or gas, through the pipeline serves to propel the pig within the pipeline.
While the improved cup of this disclosure may be employed on many types of pigs, such as those used for cleaning the interior of a pipeline, the advantages of the improved cup are particularly helpful and important when used on an instrumentation type pig, and the cup will be described as it is particularly applicable for this purpose.
2. The Prior Art
For background information relating to pipeline pigs that employ resilient cups reference may be had to the following U.S. patents:
______________________________________ U.S. Pat. No. Title Inventor Issue Date ______________________________________ 4,984,322 Elastomeric Disc For Cho et al Jan 15, 1991 Use On A Pipeline Pig 4,953,412 Pipeline Caliper Pig Rosenberg Sep 04, 1990 4,930,223 Bend Detector Pig Smith Jun 05, 1990 4,457,073 Pipeline Pig having Payne Jul 03, 1984 Improved Means Of Sensing Changes In The Internal Config- uration Of A Pipeline 4,524,526 Apparatus & Method Levine Jun 25, 1985 For Inertial Measure- ment Of Pipeline Deflection 4,880,028 Completion Machine Osburn et Nov 14, 1989 al 4,522,063 Methods & Apparatus VerNooy Jun 11, 1985 For Indicating Se- lected Physical Par- ameters In A Pipeline 4,457,073 Pipeline Pig Having Payne Jul 03, 1984 Improved Means Of Sensing Changes In The Internal Con- figuration Of A Pipeline 4,413,370 Unitary Pig For Use Payne et Nov 08, 1983 In A Pipeline al 4,365,379 Pipeline Pig Having Neff Dec 28, 1982 Improved end Plate Retention 3,940,855 Pipeline Pig VerNooy Mar 02, 1976 et al 3,887,983 Pipe Pulling Tool Province Jun 10, 1975 3,868,773 Bean Removal Tool Province Mar 04, 1975 3,862,497 Pipeline Pig VerNooy Jan 28, 1975 et al 3,755,908 Pipeline Pig VerNooy Sep 24, 1973 3,732,625 Pipeline Pig VerNooy May 15, 1973 3,704,478 Pipeline Pig VerNooy Dec 05, 1972 3,649,983 Pipeline Pig VerNooy Mar 21, 1972 3,604,041 Pipeline Cleaning VerNooy Sep 14, 1968 Device 3,600,010 Pipeline Coupling Downs et Aug 17, 1971 al 3,576,043 Pipeline Pig With Zongler Apr 27, 1971 Spring-Mounted Scrapers 3,496,588 Pipeline Pig VerNooy Jun 26, 1967 ______________________________________
In addition to the instrumentation type pigs as exemplified by these patents, examples of pigs employing cups that are primarily intended for other purposes, such as cleaning or for fluid separation, are U.S. Pat. Nos. 4,413,370 and 4,365,379.
An object of the present invention is to provide a cup having improvements over cups exemplified by these previously issued patents. The cup to be hereinafter described includes the basic capabilities of the cups illustrated in these patents, that is, for supporting a pipeline pig centrally within a pipeline and for impeding fluid flow therepast so that the pig will be propelled through the pipeline. In addition, the cup to be described has improved strength for supporting a pig body centrally within a pipeline while, at the same time, the cup has greater flexibility. That is, the improved cup of this disclosure more readily flexes inwardly to pass a protrusion in the pipeline wall. In addition, the configuration of the cup is such that it is less likely to catch on or hang up on an object extending within the pipeline wall.